How your digestive system works – Emma Bryce

How your digestive system works – Emma Bryce

Across the whole planet, humans eat on average between
one and 2.7 kilograms of food a day. That’s over 365 kilograms
a year per person, and more than 28,800 kilograms
over the course of a lifetime. And every last scrap makes its way
through the digestive system. Comprised of ten organs
covering nine meters, and containing
over 20 specialized cell types, this is one of the most diverse
and complicated systems in the human body. Its parts continuously work in unison
to fulfill a singular task: transforming the raw materials
of your food into the nutrients and energy
that keep you alive. Spanning the entire length of your torso, the digestive system
has four main components. First, there’s the gastrointestinal tract, a twisting channel
that transports your food and has an internal surface area
of between 30 and 40 square meters, enough to cover half a badminton court. Second, there’s the pancreas, gallbladder, and liver, a trio of organs that break down food
using an array of special juices. Third, the body’s enzymes, hormones, nerves, and blood all work together to break down food, modulate the digestive process, and deliver its final products. Finally, there’s the mesentery, a large stretch of tissue that supports and positions all your digestive organs
in the abdomen, enabling them to do their jobs. The digestive process begins
before food even hits your tongue. Anticipating a tasty morsel, glands in your mouth start
to pump out saliva. We produce about 1.5 liters
of this liquid each day. Once inside your mouth, chewing combines with the sloshing saliva to turn food into a moist lump
called the bolus. Enzymes present in the saliva
break down any starch. Then, your food finds itself at the rim of a 25-centimeter-long tube
called the esophagus, down which it must plunge
to reach the stomach. Nerves in the surrounding
esophageal tissue sense the bolus’s presence
and trigger peristalsis, a series of defined muscular contractions. That propels the food into the stomach, where it’s left at the mercy
of the muscular stomach walls, which bound the bolus,
breaking it into chunks. Hormones, secreted by cells in the lining,
trigger the release of acids and enzyme-rich juices
from the stomach wall that start to dissolve the food
and break down its proteins. These hormones also alert the pancreas, liver, and gallbladder to produce digestive juices and transfer bile, a yellowish-green
liquid that digests fat, in preparation for the next stage. After three hours inside the stomach, the once shapely bolus is now
a frothy liquid called chyme, and it’s ready to move into
the small intestine. The liver sends bile
to the gallbladder, which secretes it into the first portion of
the small intestine called the duodenum. Here, it dissolves the fats
floating in the slurry of chyme so they can be easily digested
by the pancreatic and intestinal juices that have leached onto the scene. These enzyme-rich juices break the fat
molecules down into fatty acids and glycerol for easier
absorption into the body. The enzymes also carry out
the final deconstruction of proteins into amino acids and carbohydrates into glucose. This happens in the
small intestine’s lower regions, the jejunum and ileum, which are coated in millions
of tiny projections called villi. These create a huge surface area
to maximize molecule absorption and transference into the blood stream. The blood takes them on the final
leg of their journey to feed the body’s organs and tissues. But it’s not over quite yet. Leftover fiber, water, and dead cells
sloughed off during digestion make it into the large intestine,
also known as the colon. The body drains out most of the remaining
fluid through the intestinal wall. What’s left is a soft mass called stool. The colon squeezes this byproduct
into a pouch called the rectum, where nerves sense it expanding and tell the body when
it’s time to expel the waste. The byproducts of digestion
exit through the anus and the food’s long journey, typically lasting between 30 and 40 hours, is finally complete.

100 Replies to “How your digestive system works – Emma Bryce”

  1. When I was a kid, my illiterate granny told me that there are pounding machines in the walls of of my stomach that crushes the food.

    Decades has gone by and I'm so glad she was right in her own way.

  2. TED-ED is the best channel on you tube to understand anything
    …………..Thank you………….

  3. Praise God for His wonderful designs. Such things cannot be explained by goo to you evolution. Come on, no one in their right, logical mind can say this is not an incredible design.

  4. I swallowed a piece of my braces (The wire part) and I’m having anxiety
    Thanks for letting me know this because I’m in pain and scared :’)))

  5. i actually see these videos lots of times cause I am not an English but i hope on day i will be the same or better than any average

  6. 3:06 裡中文翻譯錯了。 應該是「肝臟產生膽汁後 送到膽囊。膽汁再由膽囊送到十二指腸(小腸第一段)」。

  7. Why do you immediately feel that need to take a dump after eating fast food or high calorie/carb foods? Does it push food out faster? How does that work?

  8. Digestive process completed in 30-40 hours.
    That means fasting from time to time is very beneficial

    Save food for the poor

  9. Your information is very good. No one should go through this problem, in fact, my brother had this problem, then we got him treated with a good Ayurveda center Whose name is Planet Ayurveda. If you have this type of problem or any other type of health problem. you should go to Planet Ayurveda.

  10. I need a smart person to explain how the digestive system evolved? And where did food come from? Language? How did we leave "ape-hood" to become humans when apes are still here?

  11. Socio-economic and Political changes can improve/break the vicious cycle of malnutrition with specific nutrition and health intervention.
    Click here for further information:

  12. And people claim that this happened by accident😂….design is always tied to purpose. There is nothing that is designed that doesn’t have a purpose. Purpose comes first then design follows…. it begins in the mind…it is proof that there is a Designer. How can a “system” be made by chance?” All components work “together” for a goal…. even a child knows this…

  13. No mention of the all important bacteria in this system that we require to survive…after all it is titled "how your digestive system works" …….what an oversight

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